Critical areas for sediment delivery to the Chubut River, Patagonia Argentina: geomorphological evidence from the Sagmata pilot basin

Sediment discharge events in the lower basin of the Chubut River (Patagonia, Argentina) associated with rainfall events generate serious problems for drinking water purification of more than 250,000 inhabitants and the support of livestock farming activity of about 42,000 ha in the region. Identifying the areas of potential sediment contribution to the Chubut River and the conditions necessary for erosion and sediment transfer is of vital importance to mitigate the negative impact of sediment discharge into the river and to establish water management plans. We conducted a detailed geomorphological study in a 110 km 2 tributary watershed of the Chubut River (Sagmata pilot Basin), and identify potential sediment production zones. We based our analyzes on concomitant studies that indicate that the sediment remobilization is linked to the location of the drainage networks, especially in regions associated with badlands and erosional scarps formed on Paleogene continental deposits. A detailed geomorphological map in a 110 km 2 pilot watershed was constructed, with a particular emphasis in identifying sediment production zones. Fine sediment contribution to the Chubut river is linked to badlands/erosion scarps units constituted by Paleogene deposits. Identifying areas of fine sediment supply is of vital importance to mitigate the negative impact of sediment discharge into the Chubut river and to establish water management plans.